Cannot connect to QEMU VM over VNC within same network.

[dartleader]

EDIT: SOLVED. Solution was to use vncviewer's -via functionality to connect across ssh.

Hello everyone,

I'm trying to host a number of virtual machines on my server at home using QEMU. When I have a test virtual machine running, it runs on the default port 5900, and I am able to see the service running from another machine within my local network, but am unable to join.

Output of scanning the remote server from my client machine:

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 Starting Nmap 7.91 ( https://nmap.org ) at 2021-04-08 21:42 ADT
Nmap scan report for remote-server (192.168.1.101)
Host is up (0.00036s latency).

PORT     STATE  SERVICE VERSION
5900/tcp closed vnc

Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 1.64 seconds

When I try to connect to port 5900 with tigervnc's vncviewer, I get a 'connection refused' error - to nobody's surprise since the port is closed.

I have uncommented the line in /etc/libvirt/qemu.conf to allow vnc to listen to "0.0.0.0", which it states will cause it to listen to all addresses, but it has no effect.

QEMU and VNC work as expected when run on the same machine (ie: hosted on localhost), but I would like to migrate my VMs to my server and be able to connect to them remotely over wireguard.

Any help would be greatly appreciated! Thank you very much!

[mike155]

Is there a firewall on your server or on your client machine? Firewalls can cause 'closed' ports in the output of nmap.

Please run the commands below and post only the '5900/tcp' line of the output:

1. On your client machine:

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   nmap -d 192.168.1.101

2. On your server:

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   nmap -d 192.168.1.101

3. On your server:

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   nmap -d 127.0.0.1

[dartleader]

Hi Mike, output of nmap:

From client:
nmap -d 192.168.1.101 -p 5900 | rg 5900

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5900/tcp closed vnc     conn-refused

From server:
nmap -d 192.168.1.101 -p 5900 | rg 5900

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5900/tcp closed vnc     conn-refused

nmap -d 127.0.0.1 -p 5900 | rg 5900

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5900/tcp open vnc     syn-ack

Evidently it's open to the localhost but refuses other connections.

[mike155]

Thanks for the data.

What happens if you start vncviewer on your client machine with

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vncviewer -via <your_username>@192.168.1.101 127.0.0.1::5900

That should work

[dartleader]

What happens if you start vncviewer on your client machine with

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vncviewer -via <your_username>@192.168.1.101 127.0.0.1::5900

That should work

Works great! Thanks for your help Mike!